Methods and apparatus to detect and control plasma fires

ABSTRACT

Methods and systems to detect and control plasma fires are disclosed. An example method includes monitoring an optical fiber using a sensor, the optical fiber being positioned proximate a conductor through which electricity is to flow, the optical fiber not being coupled to a signal generator or a light source; identifying a change in the optical fiber, the change associated with a change in the optical fiber or a casing surrounding the optical fiber due to a plasma fire; and controlling the flow of electricity through the conductor based on identifying the change.

This patent arises from a continuation of U.S. patent application Ser.No. 13/431,432 filed Mar. 27, 2012, which is hereby incorporated hereinby reference in its entirety.

FIELD OF THE DISCLOSURE

This patent relates to methods and apparatus to detect and controlplasma fires.

BACKGROUND

Plasma fires, which may be observed in high current electronic systems(e.g., circuit boards, equipment bays, power distribution systems,etc.), are difficult to detect because they do not create an abnormallyhigh current flow through the electronic system. Thus, overcurrentprotections such as circuit breakers, fuses, electronic detectors, etc.,are typically unable to detect a plasma fire (i.e., an electronic plasmafire) even as the plasma fire is being fed more energy. In electronicsystems of aircrafts, plasma fires pose a serious danger if undetectedand uncontrolled.

SUMMARY

An example method includes monitoring an optical fiber using a sensor,the optical fiber being positioned proximate a conductor through whichelectricity is to flow, the optical fiber not being coupled to a signalgenerator or a light source; identifying a change in the optical fiber,the change associated with a change in the optical fiber or a casingsurrounding the optical fiber due to a plasma fire; and controlling theflow of electricity through the conductor based on identifying thechange.

The features, functions, and advantages that have been discussed can beachieved independently in various embodiments or may be combined in yetother embodiments further details of which can be seen with reference tothe following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an example passive plasma fire detectionapparatus that can be used to implement the examples disclosed herein.

FIG. 2 is an illustration of an example active plasma fire detectionapparatus that can be used to implement the examples disclosed herein.

FIG. 3 depicts an example method that can be used to implement theexamples disclosed herein.

FIG. 4 is a schematic illustration of an example processor platform thatmay be used and/or programmed to implement any or all of the examplemethods and apparatus disclosed herein.

FIG. 5 is an illustration of an example plasma fire detection apparatusthat can be used to implement the examples disclosed herein.

DETAILED DESCRIPTION

Certain examples are shown in the above-identified figures and describedin detail below. In describing these examples, like or identicalreference numbers are used to identify the same or similar elements. Thefigures are not necessarily to scale and certain features and certainviews of the figures may be shown exaggerated in scale or in schematicfor clarity and/or conciseness. Additionally, several examples have beendescribed throughout this specification. Any features from any examplemay be included with, a replacement for, or otherwise combined withother features from other examples.

The examples disclosed herein relate to apparatus and methods to detectand control plasma fires in, for example, aircrafts, vehicles, groundbased applications, missiles, etc. Plasma fires, which may be observedin high current electronic systems (e.g., circuit boards, equipmentbays, power distribution systems, etc.), are difficult to detect becausethey do not create an abnormally high current flow. Thus, overcurrentprotections such as circuit breakers, fuses, electronic detectors, etc.,typically are unable to detect an electronic circuit anomaly even as theplasma fire (i.e., an electronic plasma fire) is being fed more energy.

In an aircraft, a short or an arc from an electrical cable, circuitboard, electronic bay, etc., may initiate a plasma fire. Using passiveand/or active plasma fire detection apparatus, the examples disclosedherein may be used to protect highly distributed wiring and circuitsfrom the damage of a plasma fire. In the passive and active apparatus,one or more cables, optical fibers, etc., are positioned adjacent and/orproximate an electrical cable, a circuit board, an electronic bay and/orany other conductor or element where a plasma fire may occur. Aconductor is a material through which electricity flows such as, forexample, copper, silver, aluminum, etc., and may in the form ofelectrical wires, electrical cables, circuit boards, electronic bays,etc. The optical fiber may be covered to prevent ambient light fromentering the optical fiber.

In the example passive apparatus described herein, a receiver and/orsensor may be coupled to a first end of an optical cable (e.g., a darkoptical fiber) and a second end of the optical cable may be free and/ornot directly coupled to a sensor. In the example active apparatusdescribed herein, a receiver and/or sensor may be coupled to a first endof an optical cable and a transmitter may be coupled to a second end ofthe optical cable. In some examples, to enable a determination to bemade of the severity of a plasma fire, multiple cables and/or cablecasings having different melt points are used with the examplesdisclosed herein. Each optical cable may have an associated sensor,transmitter and/or receiver.

In operation of the example passive apparatus, electricity flows throughan electrical conductor, such as a cable, circuit board, an electronicbay, etc. If a plasma fire occurs, the plasma fire melts and/orphysically changes a portion of an optical cable (e.g., the opticalfiber and/or its casing), which enables a signal and/or light from theplasma fire to impinge on and be transmitted through the optical fiberto a sensor. Thus, prior to melting, the optical fiber in the examplepassive apparatus is a dark fiber (e.g., no signals are able to beconveyed through the optical fiber). Based on receiving the signal andidentifying the plasma fire (e.g., a change in the optical cable orfiber), the sensor and/or a controller coupled thereto shuts off a flowof electricity to the elements affected by the plasma fire, for example.

In operation of the example active apparatus, electricity flows throughan electrical conductor such as an electrical cable, a circuit board, anelectronic bay, etc. and a transmitter transmits a signal and/or lightsignal through an optical cable (e.g., through an optical fiber) to thereceiver. The signal may be a varying signal to enable a determinationof a temperature of the optical fiber and/or a location of a heat source(e.g., a plasma fire), if one exists, adjacent to the optical fiber. Ifa plasma fire occurs, the plasma fire melts and/or physically changes aportion of the optical cable (e.g., the optical fiber and/or its casing)to interrupt and/or change the signal received by a receiver. However,in some examples, a plasma fire may interrupt and/or change the signalreceived by the receiver without melting and/or physically changing theoptical fiber and/or its casing. In such examples, the change in theoptical fiber is associated with an increase in temperature such as achange in frequency or other characteristic of the signal beingreceived. Based on identifying the plasma fire (e.g., a change in theoptical cable), the sensor and/or controller coupled thereto shuts offelectricity flow to the elements affected by the plasma fire, forexample.

FIG. 1 depicts an example passive plasma fire detection apparatus 100that may be used to detect a plasma fire in an electrical conductor suchas a cable 102 and/or an equipment bay 104 of an aircraft such as anairplane, a helicopter, etc. In some examples, the apparatus 100includes a first portion 106 to detect a plasma fire having a first orlower temperature and a second portion 108 to detect a plasma firehaving a second or greater temperature. The first portion 106 includes afirst sensor 110 and a first optical fiber or cable 112 and the secondportion 108 includes a second sensor 114 and a second optical fiber orcable 116. The first and/or second sensors 110, 114 may be photoelectricsensors or optical receivers. The optical fibers 112 and 116 may bepositioned adjacent and/or around the electrical cable 102, theequipment bay 104, etc. If the optical fibers 112 and 116 are positionedadjacent the equipment bay 104, the optical fibers 112 and 116 may beplaced in close proximity to any components having a high enough powerlevel to be a potential source for a plasma fire. In some examples, theoptical fibers 112 and 116, which are covered by a casing to preventambient light penetration, may be embedded in and/or encased in a jacketof the electrical cable 102.

In operation, a generator or power source 118 provides electricity orelectrical power via the electrical cable 102, the equipment bay 104,etc., to a load 120. If a plasma fire is initiated by, for example, ashort or an arc from the electrical cable 102 or the equipment bay 104,heat generated from the plasma fire melts a portion of the first and/orsecond optical fibers 112 and/or 116 and/or their casings. Melting theoptical fibers 112 and/or 116 and/or exposing the optical fibers 112and/or 116 to light (e.g., the plasma fire) by melting their casingenables a light signal to be introduced into and conveyed through theoptical fiber 112 and/or 116 to the respective sensor 110, 114.

The first optical fiber 112 and/or its casing has a different or lowermelt point than the second optical fiber 116 and/or its casing. Thus,the severity and/or temperature of a plasma fire may be determined basedon which of the optical fibers 112 and/or 116 and/or casings melt. Basedon the sensors 110 and/or 114 identifying and/or receiving a lightsignal, the sensor 110, 114 and/or a processor and/or controller 122coupled thereto stops the flow of electricity from the generator 118.

While the above example describes the reference numbers 112 and 116 asbeing optical cables or fibers, in other examples, the reference numbers112 and/or 116 may correspond to metal wires or cables. A cable mayinclude a plurality of metal wires that forms a rope. In such examples,a plasma fire may change and/or cause an electrical impulse or voltagein the wire 112 and/or 116 that is detected by the respective sensor(e.g., electronic field (emf) sensor and/or a voltage sensor) 110, 114.The change in voltage is thus associated with a plasma fire.

FIG. 2 depicts an example active plasma fire detection apparatus 200that may be used to detect a plasma fire in electrical conductors suchas an electrical cable 202 and/or an equipment bay 204 of an aircraftsuch as an airplane, a helicopter, etc. In some examples, the apparatus200 includes a sensor and/or receiver 206, a transmitter 208 and anoptical cable or fiber 209 to couple the receiver 206 and thetransmitter 208. The transmitter 208 may be an optical transmitter, adiode laser, a light source or a pulse laser, and the receiver 206 maybe a photoelectric sensor, an optical receiver or a laser receiver. Theoptical cable or fiber 209 may be positioned adjacent and/or around theelectrical cable 202, the equipment bay 204, etc. In some examples, theoptical fiber 209 may be embedded in and/or encased in a jacket of theelectrical cable 202.

In operation, a generator or power source 210 provides electricity orelectrical power via the electrical cable 202, the equipment bay 204 toa load 212 and the transmitter 208 transmits a light signal through theoptical fiber 209 to the receiver 206. If a plasma fire is initiated by,for example, a short or an arc from the electrical cable 202 or theequipment bay 204, heat generated from the plasma fire melts a portionof the optical fiber 209 and/or its casing, which disturbs and/orchanges the signal being transmitted through the optical fiber 209 tothe receiver 206. However, in other examples, a plasma fire mayinterrupt and/or change the signal received by the receiver 206 withoutmelting the optical fiber and/or its casing. Based on identifying achange in the light signal received, the receiver 206 and/or a processorand/or controller 214 coupled thereto stops the flow of electricity fromthe generator 210. Alternatively, based on identifying a change in thelight signal received, the receiver 206 and/or a processor and/orcontroller 214 coupled thereto changes the flow of electricity from thegenerator 210. The change in the flow of electricity may includethrottling the flow of electricity, limiting the flow of electricity,redirecting the flow of electricity and/or adjusting the flow ofelectricity per one or more control algorithms of the processor 214. Insome examples, the control algorithms consider optic fiber routing,system power redundancies, overall safety considerations, powerrerouting pathways and/or any other considerations that would enablefurther safe operation of the aircraft or affected system.

A flowchart representative of an example method 300 for implementing thethe sensors 110, 114, the receiver 206, the processors 122, 214 and/orthe transmitter 208 is shown in FIG. 3. In this example, the method 300comprises a program for execution by a processor such as the processor402 shown in the example computer 400 discussed below in connection withFIG. 4. The program may be embodied in software stored on a tangiblecomputer readable medium such as a CD-ROM, a floppy disk, a hard drive,a digital versatile disk (DVD), a BluRay disk, or a memory associatedwith the processor 402, but the entire program and/or parts thereofcould alternatively be executed by a device other than the processor 402and/or embodied in firmware or dedicated hardware. Further, although theexample program is described with reference to the flowchart illustratedin FIG. 3, many other methods of implementing the example the sensors110, 114, the receiver 206, the processors 122, 214 and/or thetransmitter 208 may alternatively be used. For example, the order ofexecution of the blocks may be changed, and/or some of the blocksdescribed may be changed, eliminated, or combined.

As mentioned above, the example operations of FIG. 3 may be implementedusing coded instructions (e.g., computer readable instructions) storedon a tangible computer readable medium such as a hard disk drive, aflash memory, a read-only memory (ROM), a compact disk (CD), a digitalversatile disk (DVD), a cache, a random-access memory (RAM) and/or anyother storage media in which information is stored for any duration(e.g., for extended time periods, permanently, brief instances, fortemporarily buffering, and/or for caching of the information). As usedherein, the term tangible computer readable medium is expressly definedto include any type of computer readable storage and to excludepropagating signals.

FIG. 3 is an example method 300 that can be used to detect and control aplasma fire. One or more sensors 110, 114 and/or 206 may be used tomonitor and/or identify a change in the optical fibers 112, 116 and/or209 and/or a signal received therethrough (block 302). At block 304, thesensor 110, 114 and/or 206 and/or the processor 122 and/or 214 determineif a change has been identified (block 304). In some examples, thechange may be associated with a plasma fire melting a portion of theoptical fiber 112 and/or 116 and/or its casing to enable light to beinduced into and conveyed to one or more of the sensors 110 and/or 114.In other examples, the change may be associated with a plasma firechanging and/or disrupting a light signal being conveyed from thetransmitter 208 to the receiver 206. If a change is identified, thesensor 110, 114 and/or 206 and/or the processor 122 and/or 214 controlsand/or shuts off a flow of electricity through the electrical cable 102,202 and/or the equipment bay 104, 204 (block 306).

FIG. 4 is a block diagram of an example processor system 400 capable ofexecuting the instructions of FIG. 4 to implement the sensors 110, 114,the receiver 206, the processors 122, 214 and/or the transmitter 208 orany of the examples disclosed herein. As shown in FIG. 4, the processorsystem 400 includes a processor 402 that is coupled to aninterconnection bus 404. The processor 402 may be any suitableprocessor, processing unit or microprocessor. Although not shown in FIG.4, the processor system 400 may be a multi-processor system and, thus,may include one or more additional processors that are identical orsimilar to the processor 402 and that are communicatively coupled to theinterconnection bus 404.

The processor 402 of FIG. 4 is coupled to a chipset 406, which includesa memory controller 408 and an input/output (I/O) controller 410. As iswell known, a chipset typically provides I/O and memory managementfunctions as well as a plurality of general purpose and/or specialpurpose registers, timers, etc. that are accessible or used by one ormore processors coupled to the chipset 406. The memory controller 408performs functions that enable the processor 402 (or processors if thereare multiple processors) to access a system memory 412 and a massstorage memory 414.

The system memory 412 may include any desired type of volatile and/ornon-volatile memory such as, for example, static random access memory(SRAM), dynamic random access memory (DRAM), flash memory, read-onlymemory (ROM), etc. The mass storage memory 414 may include any desiredtype of mass storage device including hard disk drives, optical drives,tape storage devices, etc.

The I/O controller 410 performs functions that enable the processor 402to communicate with peripheral input/output (I/O) devices 416 and 418and a network interface 420 via an I/O bus 422. The I/O devices 416 and418 may be any desired type of I/O device such as, for example, akeyboard, a video display or monitor, a mouse, etc. The networkinterface 420 may be, for example, an Ethernet device, an asynchronoustransfer mode (ATM) device, an 802.11 device, a DSL modem, a cablemodem, a cellular modem, etc. that enables the processor system 400 tocommunicate with another processor system.

While the memory controller 408 and the I/O controller 410 are depictedin FIG. 4 as separate blocks within the chipset 406, the functionsperformed by these blocks may be integrated within a singlesemiconductor circuit or may be implemented using two or more separateintegrated circuits.

FIG. 5 depicts an example plasma fire detection apparatus 500 includingan example passive fire detection apparatus 502 and an example activefire detection apparatus 504. The example passive plasma fire detectionapparatus 502 functions similarly to the example passive plasma firedetection apparatus 100 of FIG. 1 and the example active fire detectionapparatus 504 functions similarly to the example active fire detectionapparatus 200 of FIG. 2 and, thus, the same reference numbers have beenused to identify the same or similar elements.

As set forth herein, an example apparatus includes a first optical fiberproximate a conductor through which electricity is to flow; a sensor toidentify a change in a signal received via the optical fiber, the changeassociated a physical change in the optical fiber or a casingsurrounding the first optical fiber; and a controller to control a flowof electricity through the conductor based on the change in the signal.In some examples, the apparatus is for use on an aircraft. In someexamples, the physical change is associated with the plasma fire meltinga portion of the first optical fiber or the casing. In some examples,the sensor is responsive to a light signal conveyed via the firstoptical fiber. In some examples, the first optical fiber includes a darkoptical fiber. In some examples, the apparatus includes a transmitter totransmit the signal through the first optical fiber to the sensor. Insome examples, the transmitter includes an optical transmitter, a diodelaser, a light source, or a pulse laser.

In some examples, the signal includes a varying frequency signal toenable a determination of at least one of a temperature of the firstoptical fiber or a location of a heat source adjacent the first opticalfiber. In some examples, the sensor includes at least one of aphotoelectric sensor, an optical receiver, or a laser receiver. In someexamples, the apparatus includes a second optical fiber proximate theconductor, the first optical fiber or the casing includes a first meltpoint and the second optical fiber or casing surrounding the secondoptical fiber including a second melt point.

An example apparatus includes a cable to be positioned proximate aconductor, electricity to flow through the conductor; a sensor toidentify a change in the cable, the change associated with a plasmafire; and a controller to control a flow of electricity through theconductor in response to the change. In some examples, the changeincludes a change in a voltage received by the sensor. In some examples,the change includes a physical change in the cable. In some examples,the cable includes a metal wire or an optical fiber.

An example method includes identifying a change in an optical fiber, thechange associated with a change in the optical fiber or a casingsurrounding the optical fiber, the optical fiber proximate a conductorthrough which electricity flows; and controlling the electricity flowthrough the conductor based on identifying the change. In some examples,identifying the change includes receiving a signal associated with aplasma fire melting a portion of the optical fiber or an associatedcasing. In some examples, the change includes exposing a portion of theoptical fiber to light. In some examples, identifying the changeincludes receiving a different signal from a transmitter associated witha plasma fire melting a portion of the optical fiber or an associatedcasing. In some examples, the change includes a physical change in theoptical fiber. In some examples, controlling the electricity flowincludes one or more of shutting off the electricity flow, throttlingthe electricity flow, limiting the electricity flow, redirecting theelectricity flow, or adjusting the electricity flow.

An example apparatus includes an optical fiber to be positionedproximate a conductor, the optical fiber not being coupled to a signalgenerator or light source, electricity to flow through the conductor; asensor to identify a change in the optical fiber, the change associatedwith a plasma fire; and a controller to control a flow of electricitythrough the conductor in response to the change. In some examples, theoptical fiber includes a first optical fiber and the sensor includes afirst sensor, and further including: a second optical fiber proximatethe conductor; a transmitter to transmit a signal through the secondoptical fiber; a second sensor to identify a change in the signaltransmitted via the second optical fiber, the change associated with aphysical change in the second optical fiber or a casing surrounding thesecond optical fiber; and the controller to, based on the change in thesignal: control a flow of electricity through the conductor.

In some examples, the apparatus is for use on an aircraft. In someexamples, the physical change is associated with a plasma fire melting aportion of the second cable or the second casing. In some examples, thesignal is a light signal and the second sensor is responsive to thelight signal. In some examples, the optical fiber includes a darkoptical fiber. In some examples, the apparatus includes a transmitter totransmit the signal through the cable to the second sensor. In someexamples, the transmitter includes an optical transmitter, a diodelaser, a light source, or a pulse laser. In some examples, based on thechange in the signal, the controller is to determine at least one of atemperature of the cable or a location of a heat source adjacent thecable. In some examples, the second sensor includes at least one of aphotoelectric sensor, an optical receiver, or a laser receiver.

In some examples, the optical fiber includes a first optical fiber and afirst casing surrounding the first optical fiber, the sensor includes afirst sensor, and further including a cable proximate the conductor, thefirst optical fiber or the first casing including a first melt point andthe cable or a second casing surrounding the cable including a secondmelt point, the first melt point being different than the second meltpoint; a second sensor to identify a change in a signal received via thecable, the change associated with a physical change in the cable or thesecond casing surrounding the cable, wherein the controller to control aflow of electricity through the conductor based on the change in thesignal.

In some examples, the change includes a change in a voltage received bythe cable. In some examples, the change includes a physical change inthe optical fiber. In some examples, the cable includes a metal wire oran optical fiber. In some examples, the change is associated with theplasma fire melting a portion of the optical fiber or an associatedcasing. In some examples, the physical change includes exposing aportion of the cable to light created by a plasma fire. In someexamples, the change includes a different signal received from atransmitter associated with the plasma fire melting a portion of thecable or the second casing. In some examples, the change includes anincrease in a frequency of the signal. In some examples, the sensor isresponsive to a light signal conveyed via the optical fiber, the lightsignal being generated by the plasma fire.

Furthermore, although certain example methods, apparatus and articles ofmanufacture have been described herein, the scope of coverage of thispatent is not limited thereto. On the contrary, this patent covers allmethods, apparatus and articles of manufacture fairly falling within thescope of the appended claims either literally or under the doctrine ofequivalents.

What is claimed is:
 1. A method, comprising: monitoring an optical fiberusing a sensor, the optical fiber being positioned proximate a conductorthrough which electricity is to flow, the optical fiber not beingcoupled to a signal generator or a light source; identifying a change inthe optical fiber, the change associated with a change in the opticalfiber or a casing surrounding the optical fiber due to a plasma fire;and controlling the flow of electricity through the conductor based onidentifying the change.
 2. The method of claim 1, wherein identifyingthe change includes receiving a signal associated with the plasma firemelting a portion of the optical fiber or the associated casing.
 3. Themethod of claim 2, wherein the signal is a light signal and the sensoris responsive to the light signal.
 4. The method of claim 1, wherein thechange includes exposing a portion of the optical fiber to light.
 5. Themethod of claim 1, wherein the optical fiber includes a first opticalfiber, the casing includes a first casing, and the sensor includes afirst sensor, and further including: monitoring a second optical fiberusing a second sensor, the second optical fiber being positionedproximate the conductor; identifying a change in the second opticalfiber, the change associated with a change in the second optical fiberor a second casing surrounding the second optical fiber due to theplasma fire; and controlling the flow of electricity through theconductor based on identifying the change.
 6. The method of claim 5,further including transmitting a signal through the second optical fiberusing a transmitter.
 7. The method of claim 6, wherein identifying thechange includes receiving a different signal from the transmitter. 8.The method of claim 6, wherein the transmitter is an opticaltransmitter, a diode laser, a light source, or a pulse laser.
 9. Themethod of claim 1, wherein the optical fiber includes a first opticalfiber, the casing includes a first casing, and the sensor includes afirst sensor, further including: monitoring a cable using a secondsensor, the cable being positioned proximate the conductor; identifyinga change in the cable, the change associated with a change in the cableor a second casing surrounding the cable due to the plasma fire; andcontrolling the flow of electricity through the conductor based onidentifying the change.
 10. The method of claim 9, further includingtransmitting a signal through the cable using a transmitter.
 11. Themethod of claim 10, further including, in response to the change in thesignal, determining at least one of a temperature of the cable or alocation of a heat source adjacent the cable.
 12. The method of claim10, wherein the change includes an increase in a frequency of thesignal.
 13. The method of claim 9, wherein the first optical fiber orthe first casing includes a first melt point and the cable or the secondcasing surrounding the cable includes a second melt point, the firstmelt point being different than the second melt point.
 14. The method ofclaim 9, wherein the change includes a change in a voltage received bythe cable.
 15. The method of claim 9, wherein the cable includes a metalwire or an optical fiber.
 16. The method of claim 1, wherein controllingthe electricity flow includes one or more of shutting off theelectricity flow, throttling the electricity flow, limiting theelectricity flow, redirecting the electricity flow, or adjusting theelectricity flow.
 17. The method of claim 1, wherein monitoring theoptical fiber includes monitoring the optical fiber on an aircraft. 18.The method of claim 1, wherein the optical fiber is a dark opticalfiber.
 19. The method of claim 1, wherein the sensor is at least one ofa photoelectric sensor, an optical receiver, or a laser receiver. 20.The method of claim 1, wherein the sensor is responsive to a lightsignal conveyed via the optical fiber, the light signal being generatedby the plasma fire.